The 3-D imaging technology disclosed in Stettner et al, U.S. Pat. Nos. 5,446,529, 6,133,989 and 6,414,746 provides the use of a single pulse of laser light to capture the information and content of a 2-D image along with a third dimension depth coordinate; thereby providing the 3-D coordinates of object points in its field of view. This has been referred to as flash 3-D imaging in analogy with ordinary digital 2-D cameras using flash attachments for a self contained source of light. As with ordinary 2-D digital cameras, the light reflected from an object is focused by a lens onto the focal plane of the camera, which is divided into an array of pixels called a focal plane array (FPA). In the case of a 3-D camera these pixels are “smart” and can collect data from which the time of flight of the laser pulse to the object of interest can be calculated as well as data associated with the returning laser pulse shape and magnitude. Because of the similarity to radar imaging, the laser light is also referred to as flash ladar. These flash 3-D cameras are an improvement upon designs in which one or more pixels is scanned over the field of view. They eliminate the need for a precision mechanical scanner, which is costly and high maintenance; since the location of the pixels in the focal plane may be automatically registered due to their permanent positions within an array.
An additional virtue of flash ladar is its ability to capture an entire scene in one exposure despite the rapid motion of parts or sections of targets (such as the rotary blade of a helicopter) or rapid motion of the 3D camera's sensor platform. During the time it takes light to reach the target and return to the sensor, mechanical systems typically do not move fast enough to cause pixel blurring. A time sequence of 3-D flash ladar frames comprises a 3-D movie/video of the scene.